[coreboot] mcp55_fadt patch to fix Microsoft Windows BSOD 0x000000A5 (0x00000011, 0x00000006 ....)

[David Robinson]

Hi Stefan,

I agree that your suggestion would be the right implementation to support ACPI / Legacy systems. 

I chose this implementation due to a combination of: 
	* The mcp55 code sets the smi_cmd  to 0, disabling SMM.
	* Other main boards in the coreboot source tree seem to implement the same fix.
	* I don't have datasheets for the mcp55.

An alternative to patching this change into the coreboot source tree, could be to add an FAQ to the ACPI section of the coreboot website?

David Robinson

-----Original Message-----
From: Stefan Reinauer [mailto:stepan at coreboot.org] 
Sent: 09 December 2010 22:55
To: David Robinson
Cc: coreboot at coreboot.org
Subject: Re: [coreboot] mcp55_fadt patch to fix Microsoft Windows BSOD 0x000000A5 (0x00000011, 0x00000006 ....)

* David Robinson <drobinson at bluechiptechnology.co.uk> [101209 10:40]:
> Hi,
> 
>  
> 
> The attached patch fixes a problem preventing Windows XP / 7 from booting with
> bug check error A5 (0x00000011, 0x00000006) on the Gigabyte GA-M57SLI- S4
> board. Microsoft documentation states that this bug check occurs because,
> “SCI_EN never becomes set in PM1 Control Register”. This patch sets the SCI_EN
> bit. The patch applies to any board featuring the MCP55 south bridge.

Wouldn't the right way to fix this be to actually implement the
acpi_enable/acpi_disable commands on smi_cmd?

Stefan


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